Presently, micro-structure devices called MEMS (micro-electro-mechanical systems) are gaining popularity in the microelectronics industry. Such MEMS devices include, for example, micro-mechanical filters, pressure micro-sensors, micro-gyroscopes, micro-resonators, actuators, rate sensors, and acceleration sensors. These MEMS devices are created by microfabrication processes and techniques sometimes referred to as micromachining. These processes involve the formation of discrete shapes in a layer of semiconductor material by trenching into the layer with an etch medium. Because MEMS typically require movement of one or more of the formed shapes relative to others, the trenching is done in part over a cavity and in part over a substrate or bonding layer.
MEMS technology can be used to form scanning probe microscopes. Scanning probe microscopes are non-optical microscopes that use small probe tips to make measurements of a surface. One type of scanning probe microscope is the atomic force microscope. The probe tips for atomic force microscopes are typically based on micromachined silicon. In a typical probe tip arrangement, a sharpened silicon tip structure is formed at the end of a cantilever beam. Very fine surface features on a sample may be resolved using this type of microscope. Surface measurements may be made by placing the probe tip in contact with the sample surface or by placing the probe tip close to the sample surface. As the probe tip is scanned across the surface of the sample, the position of the probe tip may be monitored using a variety of methods. By processing information such as position or force data, an image of the sample surface may be generated.
The probe tips developed for use with atomic force microscopes can be adapted to a range of uses which require the measurement of extremely small objects. One such use can be storing information on a physical medium. Specifically, digital information can be stored in an extremely dense manner by placing very small bumps or holes representing ones or zeroes on the medium. An array of probe tips can be used to read, and in some cases write the stored data.
Existing techniques for fabricating probe cantilevers and tips often use Silicon on Insulator (SOI) wafers. The SOI wafers are quite expensive and can have complex CMOS integration issues. The fabrication and integration process can be cumbersome and expensive, particularly when using probe cantilevers and tips for use in a memory storage device, where a large array of probes may be needed. It is desirable to have a method for inexpensively forming single crystal cantilevers and sharpened tips which can be more simply integrated with CMOS circuitry.